Preparation of fibers from carboxymethylcellulose



Patented Jan. 31, 1950 UNITED STATES PATENT OFFICE PREPARATION OF FIBERS FROM CARBOXYMETHYLCELLULOSE Agriculture No Drawing. Application August 9, 1946, Serial No. 689,351

22 Claims. (CI. 18-54) (Granted under the act of March 3, 1883, as amended April 30. 1928; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention hereindescribed, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to the preparation of fibers from carboxymethylcellulose by extruding solutions of a soluble salt of carboxymethylcellulose into precipitating solutions of metal salts which form insoluble salts with carboxymethylcellulose.

Our process preferably employs precipitating salts of polyvalent metals, that is, metals having a valence greater than one. The expression polyvalent metal as employed herein means a metal having a valence greater than one. We have found that whereas silver nitrate precipitates a coagulated material in the form of a thread from alkaline solutions of carboxymethylcellulose, the latter has only very slight tensile strength. We have further discovered that it a salt of a polyvalent element, such aslead, copper, or aluminum, and others is used that strengths up to 2.3 grams per denier are obtained.

We have found that fibers may be produced by extruding solutions of a soluble salt of carboxymethyl'cellulose into precipitating solutions such as copper sulfate, aluminum sulfate, lead acetate, stannous chloride, or mixtures of such solutions, containing polyvalent metal ions which form insoluble salts with carboxymethylcellulose. It is preferable that the cation in the original salt of the carboxymethylcellulose does not precipitate the anion of the precipitating solution.

The precipitating solution may be an aqueous solution of a salt of a metal such as copper, aluminum, lead, tin, iron, or zinc with an acid such as sulfuric acid, acetic acid, or hydrochloric acid.

The filament, comprising the copper, aluminum, lead, tin, iron, or zinc compound of the carboxymethylcarbohydrate, may be treated with a water-soluble salt such as potassium dichromate, or chromate, or ferrocyanide, or aluminum or ferric chloride or sulfate to precipitate, partially, the metal as the dichromate, chromate, ferrocyanide, or sulfate, or chloride, and give permanent colors or novel effects.

The soluble carboxymethylcellulose salts ordinarily contain about 0.5 to 1 carboxymethyl group per glucose unit.

Our new fibers have a number of useful prop- 2 erties. The metals therein lend resistance to deleterious action of microorganisms and favorably affect the rot-proofness. The colors of the fibers are fadeproof. Copper imparts a blue color; iron, a red color; chromates, a yellow color.

Filaments were made using the corresponding carboxymethyl derivative of starch. No attempt was made to separate the straight chain and branch chain fractions of the sweetpotato starch used and although filaments were prepared, the strength was lower than those made from cellulose, once the water of plasticization was lost.

Details of preparations are given in the following examples. The concentrations of soluble carboxymethylcellulose and of precipitating solutions are given only as examples and are not to be considered as limiting. The former may be as concentrated as it is possible to extrude. The latter may either be concentrated or dilute depending on the conditions, such as speed of spinning, temperature of solutions, and concentrations of the soluble carboxymethylcellulose.

Example 1 A 5% aqueous solution of the sodium salt of carboxymethylcellulose was prepared and carefully centrifuged and filtered to remove insoluble fibrous particles. This solution was extruded through a 52-hole spinnerette into an 8% lead acetate solution. The multi-filament yarn was collected on a rotating tube revolving at such speed that some stretching occurred. The fiber had a denier of 98 and a tensile strength of 1.1 grams per denier. It was brittle and was plasticized by treatment with a 5% solution of dibutyl phthalate in ethyl alcohol. After drying, this yarn had a satisfactory feel and was not brittle. The denier was then 93 and the strength 0.74 gram per denier. The fiber containing lead was treated with a number of salts with interesting results. For example, treatment with aqueous aluminum sulphate produced an opaque, white fiber due to some production of lead sulphate; treatment with very dilute aqueous potassium dichromate, when presumably lead chr0- mate is formed, due to some double decomposition, produces a beautiful yellow fiber, treatment with very dilute aqueous ferric chloride, 9. dark red fiber, and treatment of copper carboxymethylcellulose fiber with a very dilute solution of potassium ferrocyanide gave areddish brown fiber. Dilute solutions of potassium salts were necessary to prevent complete displacement with consequent formation of the soluble potassium salt of earboxymethylcellulose. These fibers may, in turn, be treated with solutions of -metaliic salts to produce fibers with different properties. For example the lead or copper content may be returned to the fiber by treatment with soluble lead or copper salts.

Example 2 Fiber was spun through a 52-hole spinnerette on a pilot size spinning machine. The precipitating solution used was 3.8% copper sulphate and 2.6% aluminum sulphate. The fiber was extruded at approximately 28 meters per minute. At this rate coagulation was too slow at room temperature but proceeded smoothly at 55 C. Approximately 30% stretch was given and the product was washed with water at 80 C. during part of the stretching. a denier of 148.2 and a tensile strength of 1.00 grams per denier. Part of the product was plasticized as in Example 1 with di-butyl phthalate. Other plasticizers were used such as di-methyl phthalate, olive oil in acetone, and glycerol.

Example 4 A aqueous solution of sodium salt of carboxymethylcellulose containing 5% triacetin (by weight of carboxymethylcellulose) was extruded through a 52-hole spinnerette into solution of 8% lead acetate at room temperature. Samples of the multifilament fiber were washed with 60 C. water, then placed under various amounts of tension during drying. Denier ranged from 267.5 to 566.1 and tensile strength from 0.95 to 1.41 grams per denier depending on amount of tension. Much of the unplasticized fibers brittleness was eliminated through use of triacetin.

Example 5 The carboxymethyl ether of starch was prepared by mixing 100 grams of raw starch (commercialsweetpotato) with 100 grams of chloroacetic acid dissolved in 100 grams of water. the mixture was added slowly, with cooling, 220 grams of 50% sodium hydroxide solution. The temperature of the rubber-like mass rose as high as 52 C. The product was mixed with sufiicient 9% hydrochloric acid, with cooling, to neutralize to phenolphthalein endpoint. The starch ether was precipitated by addition of ethyl alcohol and purified by dissolving in H and re-precipitating with alcohol. A copper salt of the soluble product contained 10.5% copper indicating an etherification of approximately 0.76 groups per glucose unit. A 10% solution of the sodium salt of carboxymethyl starch was prepared, carefully filtered and extruded through a 52-hole spinnerette into an 8% lead acetate solution. The resulting fiber was rather brittle after drying. Use of triacetin as a plasticizer made the fiber somewhat less brittle.

Having thus described our invention, we claim:

1. A process of making a fiber comprising ex- 75 The product had truding a solution in water of a salt of carboxyniethylcellulose, the carboxymethylcellulose containing about 0.5 to 1 carboxymethyl group per glucose unit through a filament forming aperture into a precipitating solution containing a salt of polyvalent metal that forms a waterinsoluble precipitate with carboxymethylcellulose, thereby forming a filament comprising the corresponding metal compound of carboxymethylcellulose no acid being added to the precipitating solution, whereby the salt of the polyvalent metal reacts directly with the salt of carboxymethylcellulose.

2. A process as in claim 1 in which the precipitating solution contains a salt of aluminum.

3. A process as in claim 1 in which the precipitating solution contains a. salt of copper.

4. A process as in claim 1 in which the precipitating solution contains a salt of lead.

5. The process oi claim 1 in which the precipitating solution contains copper and aluminum salts.

6. The process of claim 1 in which the precipitating solution contains salts of more than one polyvalent metal.

7. The process of claim 1 in which the filament is subsequently treated with a salt of another metal to displace, partially, the original metal.

8. A process of making a fiber comprising exruding an aqueous solution of a salt of carboxymethylcellulose, the carboxymethylcellulose containing about 0.5 to 1 carboxymethyl group per glucose unit through a filament forming aperture into a precipitating solution containing a salt of polyvalent metal that forms a waterinsoluble precipitate with carboxymethylcellulose, thereby forming a filament comprising the corresponding metal compound of carboxymethyleellulose, and subsequently treating the filament with an aqueous solution of a salt of another metal, the anion of which latter salt forms a water-insoluble salt with the first mentioned metal, whereby the cation of the latter metal is partially displaced in the carboxymethyl group.

9. The process of claim 8 in which the first mentioned metal is lead and the anion of the second mentioned salt is a chromate ion.

10. The process of claim 8 in which the first mentioned metal is copper and the anion of the second mentioned salt is ferrocyanide ion.

11. The process of claim 8 in which the first mentioned metal is lead and the anion of the second mentioned salt is sulfate ion.

12. A process of making a fiber comprising extruding a solution in water of a water-soluble salt of a carboxymethylcarbohydrate of the group consisting of carboxymethylcellulose and boxymethylcarbohydrate, thereby forming a filament comprising the corresponding metal compound of the carboxymethylcarbohydrate no acid being added to the precipitating solution, whereby the salt of the polyvalent metal reacts directly with the salt of carboxymethylccllulose.

13. A fiber comprising a filament of a polyvalent metal salt of a carboxymethylcarbohydrate of the group consisting of carboxymethylcellulose and carboxymethylstarch prepared by the process of claim 12.

14. A fiber comprising a filament of polyvalent metal salt of vcarboxymethylcellulose prepared by the process of claim 1.

15. A fiber comprisin a filament of a salt of carboxymethylcellulose with a metal of the group consisting of copper, aluminum, lead, tin, iron, and zinc prepared by the process of claim 1.

16. A fiber comprising a filament of more than one polyvalent metal salt of carboxymethylcellulose prepared by the process of claim 1.

17. A fiber comprising a filament 01' a polyvalent metal salt of a carboxymethylcarbohydrate of the group consisting of carboxymethylcellulose and carboxymethylstarch prepared by the proces of claim 12, and a plasticizer.

18. The process of making a fiber comprising extruding an aqueous solution of sodium carboxymethylcellulose through a filament forming aperture into a precipitating solution consisting of aqueous lead acetate to form a filament of lead carboxymethylcellulose, and treating the filament with a dilute solution of potassium chromate, thereby iorming a filament of lead carboxymethylcellulose colored yellow by chromate.

19. The process of making a fiber comprising extruding an aqueous solution of sodium carboxymethylcellulose through a filament forming aperture into a precipitating solution consisting of aqueous copper sulfate and aluminum sulfate, thereby forming a filament comprising copper and aluminum carboxymethylcellulose.

20. A copper-aluminum carboxymethylcellulose filament, the carboxymethylcellulose containing about 0.5 to 1 carboxymethyl group per lucose unit, the filament being obtained by extruding an aqueous solution of an alkali metal salt of said carboxymethylcellulose into a precipitating solution substantially consisting 01' an aqueous solution or a salt or copper and a salt of aluminum 21. A carboxymethylcellulose polyvalent metal salt filament, the carboxymethylcellulose containing about 0.5 to 1 carboxymethyl group per glucose unit, prepared by extruding'a solution substantially consisting of a solution in water of an alkali metal salt of said carboxymethylcellulose, into a precipitating bath essentially consisting ot a solution in water of a salt of a polyvalent metal that forms a water-insoluble precipitate with carboxymethylcellulose.

22. The filament defined in claim 21 in which the polyvalent metal is lead.

. JOHN DAVID um.

GEORGE c. DAUL.

REFERENCES crrrzn The following references are of record in the file of this patent:

UNITED STATES PATENTS I o'rnna REFERENCES Application of Dyestuil's by J. M. Matthews,

N. Y. John Wiley 8: Sons Inc. 1920; DD. 513-515. (Copy in Division 43.) 

1. A PROCESS OF MAKING A FIBER COMPRISING EXTRUDING A SOLUTION IN WATER OF A SALT OF CARBOXYMETHYLCELLULOSE, THE CARBOXYMETHYLCELLULOSE CONTAINING ABOUT 0.5 TO 1 CARBOXYMETHYL GROUP PER GLUCOSE UNIT THROUGH A FILAMENT FORMING APERATURE INTO A PRECIPITATING SOLUTION CONTAINING A SALT OF POLYVALENT METAL THAT FORMS A WATERINSOLUBLE PRECIPITATE WITH CARBOXYMETHYLCELLULOSE, THEREBY FORMING A FILAMENT COMPRISING THE CORRESPONDING METAL COMPOUND OF CARBOXYMETHYLCELLULOSE NO ACID BEING ADDED TO THE PRECIPITATING SOLUTION, WHEREBY THE SALT OF THE POLYVALENT METAL REACTS DIRECTLY WITH THE SALT OF CARBOXYMETHYLCELLULOSE. 